- The most sweeping ruling could come from a challenge to California's ban on same-sex marriage, established in 2008 by a ballot initiative known as Proposition 8. If the court agrees with the lower courts that denying marriage rights to same-sex couples is unconstitutional, then marriage bans in California and 34 other states could potentially be struck down as early as Monday.

- The high court may also rule that a state cannot eliminate marriage equality after granting it (which it did initially for several months in 2008 after a state Supreme Court ruling) and strike down the California ban only.

- The court could also decline to rule if it decides that the case was improperly granted judicial review or that the supporters of the California ban do not have standing to defend it in court. If the court declines to rule, only the California ban would be eliminated, and further legal challenges would be necessary to establish marriage equality nationwide. During oral arguments in March, Justice Anthony Kennedy, who may hold a key swing vote on the case, questioned whether it was properly granted review by the court and wondered if the court should wade into the "uncharted waters" of marriage rights.

- If the court rules that state bans on same-sex marriage are constitutional, then bans will remain in effect in California and in other states.

- The court may also find that marriage alternatives, civil unions and domestic partnerships, are "separate and unequal," which would allow couples to marry in California and seven other states that recognize civil unions and domestic partnerships in addition to the 12 states that recognize gay marriage. This view has support in the Obama administration, but not among the Supreme Court justices, so such a ruling is unlikely, according to legal experts at the widely respected SCOTUSblog.

United States v. Windsor: The DOMA Challenge

The Supreme Court is also expected to decide on a challenge to the Defense of Marriage Act (DOMA), which prohibits same-sex couples married in states where marriage is legal from receiving federal benefits. The Obama administration has refused to defend DOMA, and the Supreme Court is expected to either strike down or uphold the law.

Rulings on these historic civil rights cases could come down as early as Monday morning. Visit Truthout for breaking news and updates.

- The most sweeping ruling could come from a challenge to California's ban on same-sex marriage, established in 2008 by a ballot initiative known as Proposition 8. If the court agrees with the lower courts that denying marriage rights to same-sex couples is unconstitutional, then marriage bans in California and 34 other states could potentially be struck down as early as Monday.

- The high court may also rule that a state cannot eliminate marriage equality after granting it (which it did initially for several months in 2008 after a state Supreme Court ruling) and strike down the California ban only.

- The court could also decline to rule if it decides that the case was improperly granted judicial review or that the supporters of the California ban do not have standing to defend it in court. If the court declines to rule, only the California ban would be eliminated, and further legal challenges would be necessary to establish marriage equality nationwide. During oral arguments in March, Justice Anthony Kennedy, who may hold a key swing vote on the case, questioned whether it was properly granted review by the court and wondered if the court should wade into the "uncharted waters" of marriage rights.

- If the court rules that state bans on same-sex marriage are constitutional, then bans will remain in effect in California and in other states.

- The court may also find that marriage alternatives, civil unions and domestic partnerships, are "separate and unequal," which would allow couples to marry in California and seven other states that recognize civil unions and domestic partnerships in addition to the 12 states that recognize gay marriage. This view has support in the Obama administration, but not among the Supreme Court justices, so such a ruling is unlikely, according to legal experts at the widely respected SCOTUSblog.

United States v. Windsor: The DOMA Challenge

The Supreme Court is also expected to decide on a challenge to the Defense of Marriage Act (DOMA), which prohibits same-sex couples married in states where marriage is legal from receiving federal benefits. The Obama administration has refused to defend DOMA, and the Supreme Court is expected to either strike down or uphold the law.

Rulings on these historic civil rights cases could come down as early as Monday morning. Visit Truthout for breaking news and updates.